CTLA-4 agonists are used to treat conditions such as rheumatoid arthritis, psoriatic arthritis, and juvenile idiopathic arthritis. They also have other uses, such as preventing organ rejection in kidney transplant recipients. These medications broadly work by targeting the CTLA-4 protein, which helps to regulate your immune response. CTLA-4 agonists are available in injectable forms. Examples include Orencia (abatacept) and Nulojix (belatacept).